1. Field of the Invention
The present invention relates to a radial tire for heavy-duty road vehicles, and more specifically to an improvement in tread pattern formed on a tire tread, which can maintain excellent antiwet skidding performance while keeping a good tire external appearance until the tire is worn out.
2. Description of the Prior Art
In radial tires for heavy-duty road vehicles such as trucks or buses, special tread patterns are formed in order to provide good antiwet skidding performance and good tire external appearance. FIGS. 1A and 1B show an example of these prior-art tread patterns, in which a plurality of main circumferential grooves 10 are arranged at regular intervals in the tire transverse direction on the tire tread surface and further a plurality of platforms 30 are formed also at regular intervals in the tire circumferential direction on tire land portion 20 formed between two main circumferential grooves 101 and 102 in such a way to provide a height difference H down from the land portion 20.
In the above-mentioned prior-art tread pattern, since the surface of the land portion 20 wears away more when compared with that of the platform 30, the height difference H between the two decreases with increasing tire travel distance, thus resulting in a problem in that as the tire travel distance increases, not only the good tire external appearance cannot be kept, but also the good antiwet skidding performance is not maintained.